1. Field of the Invention
The present invention generally relates to an improved light module with LED light source for LCD panel. More specifically, the present invention relates to an improved light module with LED light source for LCD panel wherein Light-receiving surfaces of LGP (light guide plate), light-receiving surfaces of LGS (light guide stick) or light-emitting surfaces of LGS are coated with the mixed fluorescent powder and the white light with triple wavelength is made by the light rays emitted from UV LED to excite the mixed fluorescent powders.
2. Description of the Prior Art
The visions of the liquid crystal display (LCD) are extremely excellent since the displayed figures or pictures are not offensive to the eyes of human being unlike light emitting diode (LED). But it is one of the drawbacks of LCD that an additional light module is needed in order to show figures or pictures on the screen under the dark circumstance because LCD does not have the character of light-emitting itself.
The light rays emitted from LED 102 in the front light module of the LCD panel 100 are guided into the surface of the LCD panel 108 through LGS 104 and LGP 106. FIG. 1A and FIG. 1B show the structure of conventional front light module and the passing paths of the light rays in this structure are illustrated as the arrows of the FIG. 1A and FIG. 1B, wherein the spectrum figure of the white light LED with the double wavelength protected by Nichia's patents is adopted as shown in FIG. 2.
FIG. 3 shows the rear light module 300 of the LCD panel, wherein the light rays emitted from LED 302 are guided into the surface of the LCD panel 308 through LGP 306, the reflector sheet 305, the diffuser sheets 307 and the prism sheets 309. The numbers of the diffuser sheets 307 and the prism sheets 309 depend on the design of the rear light module 300 of the LCD panel. The passing paths of the light rays in the conventional back light module are illustrated as the arrows of FIG. 3. The white light LED with the double wavelength protected by Nichia's patents is adopted as illustrated in FIG. 3.
It is well known that mixing many kinds of color lights can form a white light. For example, the white light with double wavelength seen by the eyes of human being is formed by mixing the blue and yellow lights and the white light with triple wavelength is formed by mixing the blue, green and red lights. Presently the marketed products of emitting the white light with double wavelength are made by the chip emitting a blue light to excite the YAG fluorescent powders. In the future the products of emitting the white light with triple wavelength by the chip emitting a ultraviolet ray to excite the RGB fluorescent powders are more popular because the advantages of the organic single-layer LED with triple wavelength white light are the lower cost and easier production.
It is the NICHIA's technology that the InGaN chip 402 can emit blue lights with 460 nm wavelength is coated with the YAG fluorescent powders layer 404 as illustrated in the structure view of white light LED as FIG. 4, the yellow lights with 555 nm wavelength are formed by the blue lights emitted from LED to excite the YAG fluorescent powders. Then mixing the blue and yellow lights can make the visible white light because the two color lights are complementary. Another technology of white light LED based on the ZnSe material is developed by Sumitomo Electric Industries. The white light LED can be used in the lighting of our ordinary life or the light source of the light module of LCD panel. The developed countries such European, America and Japan already spent lots of manpower and established the special institutions to promote the development of white light LED. Since the key technology and the patents of blue light are presently owned by few companies such as NICHIA, it is not easy for the Taiwan companies that are good at in the mass production and the cost reduction to produce the white light LED. Hence, the manufacturing cost can not be reduced due to the expensive price of white light LED for the manufacturers of LCD.